Pollinator shift ensures reproductive success in a camouflaged alpine plant

Abstract

Background and Aims There are intrinsic conflicts between signalling to mutualists and concealing (camouflaging) from antagonists. Like animals, plants also use camouflage as a defence against herbivores. However, this can potentially reduce their attractiveness to pollinators. Methods Using Fritillaria delavayi, an alpine camouflaged plant with inter-population floral colour divergence, we tested the influence of floral trait differences on reproduction. We conducted pollination experiments, measured floral morphological characteristics, estimated floral colours perceived by pollinators, analysed floral scent, and investigated the reproductive successes in five populations. Key Results We found that the reproduction of F. delavayi depends on pollinators. Under natural conditions, a flower-camouflaged population had a 100% fruit set and similar seed set to three out of four yellow-flowered populations. Bumblebees are important pollinators in the visually conspicuous yellow-flowered populations, whereas flies are the only pollinator in the flower-camouflaged population, visiting flowers more frequently than bumblebees. The camouflaged flowers cannot be discriminated from the rock background as perceived by pollinators, but may be located by flies through olfactory cues. Conclusions Collectively, our results demonstrate that the flower-camouflaged population has different reproductive traits from the visually conspicuous yellow-flowered ones. A pollinator shift from bumblebees to flies, combined with high visitation frequency, compensates the attractiveness disadvantage in camouflaged plants.